### SECTION 1.0 INTRODUCTION

BRYAN A. STIRRAT & ASSOCIATES

### 1.0 INTRODUCTION

1.1 PURPOSE

PCFS FCPCMP This Final Closure and Post-Closure Maintenance Plan (FCPCMP) for the Picacho Cutand Fill Site (PCFS), SWIS No. 13-AA-0012, has been prepared for the County of Imperial Department of Public Works (CIDPW) by Bryan A. Stirrat & Associates, Inc. The PCFS FCPCMP has been prepared in accordancewith the Code of Federal Regulations (CFR) Title 40, Part 258, Subpart F. The PCFS is located on land occupied bythe Quechan Indian Tribe. These Tribal lands are held in trust by the federal governmentand are not underthe authority ofthe State ofCalifornia. Therefore, the Quechan Tribal Council has the authorityto regulate the Tribal environment. As a result, this FCPCMP for the PCFS will be subject to their review and inputwith final approval and by the United States Environmental Protection Agency (USEPA) Region 9 with the Quechan Tribal Council's concurrence. Since the PCFS is situated on Indian land, the governing Municipal Solid Waste (MSW) landfill regulations for the closure ofthe facility are found in the Federal Code of Regulations, Title 40, Part 258 (40 CFR 258). However, itshould be noted thatfor certain aspects ofthe closure and post-closure requirements, not specifically outlined in the Code of Federal Regulations, California standards (i.e., Title 27 ofthe California Code of Regulations), which are more stringentthan the Federal regulations, will be used as guidance. Certain variations from thefederal regulations (i.e., 40 CFR 258) must be approved bythe EPA as described in a documententitled, "Site-Specific Flexibility Requests for Municipal Solid Waste Landfills in Indian Country - Draft Guidance" (EPA, August 1997). Included in the guidance documentare the requirements and instructionsfor preparing a site-specific flexibility request (SSFR) for modifying the list ofgroundwater monitoring parameters from those specified in 40 CFR 258.54(a). GeologicAssociates (GLA) has prepared a SSFR to modifythe list ofdetection monitoring parameters provided in 40 CFR 258.54(a)(1) and (2). The groundwater SSFR was prepared based on information summarized in the semi-annual water quality monitoring reports prepared by GLAfor the CIDPW, includingthe first semi-annual 2009 and the annual report dated April 2010, and the EPA (August 1997) SSFR guidance document. The 1-1 ):\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec1.Doc:10/20/2010groundwater SSFR (dated September 201 0) is included as Appendix C-1 ofthe FCPCMP. In addition, an SSFR has been prepared by GLA to demonstrate thatthe proposed alternative final cover system meets the requirements of40 CFR 258.60(b). The final cover SSFR was prepared based on information summarized in the Preliminary Alternative Cover Evaluation and Design Report (see Appendix D) for the PSWS Final Closure prepared by GLA (May 1999) and the EPA (August 1997) SSFR guidance document. The alternative final cover SSFR (dated March 2008) is included as Appendix D-1 ofthe FCPCMP. The sections titled Introduction (Section 1.0) and Existing Environmental Control and Monitoring Systems (Section 2.0) ofthis document present information which is common to both the Closure Plan (Section 3.0) and Post-Closure Maintenance Plan (Section 4.0). The Post-Closure Emergency Response Plan and Closure/Post-Closure Maintenance Cost Estimate are presented in Sections 5.0 and 6.0, respectively. Certification ofClosure (Section 7.0), Recordkeeping (Section 8.0) and References (Section 9.0) comprise the remaining sections of this document. 

### 1.2 SITE LOCATION

PCFS FCPCMPThe PCFS is located in the southeastern portion ofthe Imperial Valley approximatelyfour and one half miles north ofWinterhaven and one and a half miles north ofthe All American Canal (Figure 1). The site is situated in a rural area atthe base ofthe Cargo Muchacho Mountains. The legal description ofthe site by the governmentsurvey method is: a portion ofthe Northeastquarter of Section 35, Township 15 South, Range 22 East, San Bernardino Baseline and Meridian. The approximate latitude ofthe site is 32° 48' 51" N and the approximate longitude is 114° 37' 13"W. The site is located within the Fort Yuma Indian Reservation occupied bythe Quechan Indian Tribe. As discussed in detail in Section 1.1, the Quechan Tribal Council has the authorityto regulate theTribal environmentand this FCPCMP will be subjectto their review and input with final approval made by the USEPA Region 9 with the Quechan Tribal Council's concurrence. Access to the landfill is off Picacho Road as shown on Figure 1. Vehicles travel along Picacho Road, atwo-lane, gravel roadway, and then turn intothe landfill 1-2 J:\lmperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec1.Doc:10/20/2010entrance located on the site's western boundary. This road provides access to the pesticide container disposal area located in the northern area ofthe site. 

### 1.3 CLOSURE DATE The disposal area footprintwas delineated recently through trenchings and ground surveys and is approximately 12.5 acres as shown on Figure 5. The engineering design plans presented in this FCPCMP reflect this 12.5-acre footprint area. The remaining site capacity is based on the difference between the existing topography and the final disposal area contours. Table 1 presents information regarding gross air space, final, intermediate and daily cover requirements and remaining refuse capacity. The remaining refuse capacity atthe site as ofJanuary 2009 is estimated to be approximately 2,059 cy (based on a refuse to soil volume ratio of5:1 and an in-place refuse density of0.5 tons/cy). Itshould be noted thatthe current remaining site capacity included in this document reflects the maximum utilization ofthe 12.5-acre refuse area footprint. With the total remaining refuse volumefor the site atapproximately2,059 cy (see AppendixA) and an annual average inflow rate of 1,743 cubicyards per year, the landfill's service life is estimated to be approximately 1.2 years (see Table 1) from January 2009. 

### 1.4 SURROUNDING LAND USE

PCFS FCPCMP Adjacentzoning and surrounding land use is compatiblewith the landfill operations. Land use within aone-mile radius ofthe site is located within the FortYuma Indian Reservation, which is designated as open space (S) for purposes ofcounty zoning, and there are no structures located within 1,000feet ofthe PCFS. However, this land is notsubject to county zoning requirements or designations; the land is underthe authority ofthe Quechan Tribal Council. There are currently no zoning ordinances within the Tribal land. No known inconsistencies or incompatibilities exist with the surrounding land uses and no potential adverse land use impacts are foreseeable dueto continued operation and eventual closure ofthe landfill.

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### 1.5 POST-CLOSURE SITE USE

PCFS FCPCMP 

### The currently proposed post-closure use ofthe PCFS will be non-irrigated open space. No known inconsistencies or incompatibilities exist with the surrounding land uses as there are no zoning ordinances setforth by the QuechanTribal Council within or surrounding the PCFS area. Additionally, no potential adverse land use impacts are foreseeable due to continued operation and eventual closure ofthe landfill.

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## SECTION 2.0 EXISTING ENVIRONMENTAL CONTROL AND MONITORING SYSTEMS

BRYAN A. STIRRAT &

**ASSOCI~TES**

## 2.0 EXISTING ENVIRONMENTAL CONTROL AND MONITORING SYSTEMS 2.1 LANDFILL GAS CONTROL/MONITORING SYSTEM A landfill gas control or monitoring system does notcurrently exist at the PCFS. Previous landfill monitoring utilizing the bar probe method during the regulatory agency inspections have indicated no gas migration or surface emission problems. In addition, due to the sites remote location, landfill gas migration would not create a hazard or nuisance to the public. Itshould also be noted thatthe landfill's total refuse capacity of645,333 cy is much less than the 2.5 million cubic meter threshold, which triggers the applicability of40 CFR part60, SubpartWWW. Therefore, no landfill gas collection and control system is required at the PCFS. The CIDPW has implemented a Solid Waste Gas Sampling and Reporting Program, which includes quarterly surface monitoring atthe perimeter ofthe landfill. The last eightquarters of methane gas detection monitoring results are included in Appendix H. 

### 2.2 

### GROUNDWATER MONITORING SYSTEM

PCFS FCPCMP Initially, because California is an EPA-approved State regulating solid waste facilities within the State, the site was thoughtto fall underthejurisdiction ofthe California Regional Water Quality Control Board - Colorado River Basin Region, and site monitoringwas performed in accordancewith site-specific Waste Discharge Requirement No. 88-005, and the more recent blanketWaste Discharge Requirements No. 93-071, established for all active landfills within the Colorado River Basin Region and prepared to complywith federal regulations

. As a result, the groundwater monitoringwells have been monitored by the County on a semi-annual basis beginning in November 1994 in accordance with these WDRs

. Accordingly, the semiannual detection monitoring program complies with EPA regulation 40 CFR 258.54(a) to includethe constituents listed in Appendix I, with the exception ofthe 15 heavy metals, which are included in the sampling program every 5 years. The existing groundwater monitoring system atthe PCFS consists ofthree monitoringwells (P-MW-1, 2, and 4) and onewater level measuring station (P-DW3A). Although the groundwater gradient is nearlyflat, typically well P-MW-1 is located upgradient ofthe landfill, well P -MW-4 is located down-gradientofthe 2-1 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec2.Doc:10/20/2010PCFS FCPCMP landfill's pesticide disposal area, and wells P-MW-2 and P-DW-3A are located downgradientofthe landfill. A proposed well (P-MW-5) is anticipated to be located cross-gradient ofthe landfill on the east side ofthe site. The locations of the existingwells and proposed well P-MW-5 are shown on Figure 2. All ofthe existing groundwater monitoringwells were installed by ENVIRON in August, 1994and were constructed oftwo-inch diameter PVC casing with fifteen feet of screen. All ofthe existing wells are secured at the surface with a locking steel protective cover set in concrete and a padlock. Well construction logs are included in Appendix B. Monitoringwells (P-MW-1, P-MW-2, P-MW-4) are sampled semi-annually in accordance with the Sampling and Analysis Plan (included in Appendix 

### C) using dedicated bailers. The Sampling and Analysis Plan complies with 40 CFR 258.53. Protocols for proposed monitoringwell P-MW-5 are anticipated tofollowthe same sampling and analysis plan as established for the existing monitoringwells. As discussed in Section 1.1, GLA has prepared aSSFR to modifythe list of detection monitoring parameters provided in 40 CFR 258.54{a)(1) and {2). This SSFR is included in Appendix C-1. Groundwater samples are analyzed for the Appendix I list ofvolatile organic compounds {VOCs) provided in 40 CFR, Part 258, arsenic (since itis potentially associated with some pesticides) and the metal surrogates (chloride, nitrate as nitrogen, sulfate, and total dissolved solids). In addition, field parameters (pH, dissolved oxygen, electrical conductivity, turbidity, and temperature) are also measured during sampling. Every five years, the groundwater monitoringwells are analyzed forthe full suite ofconstituents ofconcern (COCs) listed in Appendix II of40 CFR, Part 258. COC samplingwas last performed at the PCFS in August 2006, and is scheduled for sampling duringthe Winter/Spring 2011 monitoring event. In addition, following construction ofproposed well P-MW-5, samples from this well will be analyzed forthe entire 40 CFR 258 Appendix I list ofparameters (including the metals) for at least two semiannual monitoring events. During each semi-annual monitoring period, the surface monuments and well casings are inspected for security and damage. Any problems with the wells that are reported on the field data sheets are relayed to the CIDPW. Ifsignificant damage to awell is observed, then the CIDPWwill initiate a maintenance program to address the problem. 2-2 !:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec2.Doc:10/20/2010

### 2.3 

### LEACHATE COLLECTION AND REMOVAL SYSTEM/MONITORING The PCFS is unlined and predates the requirements to install a leachate collection and removal system (LCRS)

. Therefore, LCRS monitoring is not performed at the site. To date, no leachate seeps have been observed at the landfill. 

### 2.4 

### STORMWATER MONITORING

PCFS FCPCMP As authorized by the Clean WaterAct, the National Pollutant Discharge Elimination System (NPDES) permit program controlswater pollution by regulating pointsources that discharge pollutants intowaters ofthe United States. The CIDPW is currently working on submitting a Noticeof Intent (NOI) underthe Multi-Sector General Permit and developing a Stormwater Pollution Prevention Plan (SWPPP) and Stormwater Monitoring Plan (SWMP) for the PCFS.

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### SECTION 3.0 CLOSURE PLAN

BRYAN A. STIRRAT & ASSOCIATES

### 3.0 CLOSURE PLAN

3.1 INTRODUCTION Closure ofthe PCFS will be performed in accordance with applicable regulatory standards included in 40 CFR, Part 258, Subpart F. In some cases, the California standards, which are being adhered to, are more stringent than the Federal regulations. The costs associated with closure ofthe PCFS are described in Section 7.0 ofthis document. The components and systems required for closure ofthe PCFS include: the final grading plan and final cover design, surface water drainage and erosion control systems, landfill gas monitoring system, groundwater monitoring system and site security. A description ofthese closure components as well as a schedule for construction ofthe PCFS closure improvements is presented in the following subsections. 

### 3.2 FINAL GRADING

PCFS FCPCMP This section describes the final grading plan proposed for the PCFS. The most currenttopographic map (dated June 12, 2006} has been used as the base map for the final grading plan (Figure 5}. Upon cessation of refuse disposal operations, the deck area will be set ata gradient ofthree percentto facilitate drainage and accommodateforfuture differential settlement ofthe underlyingwaste. The proposed drainage control system provides for the handling ofon-site surface flows as well as the diversion of potential run-on from surrounding areas. The drainage control system consists ofdrainage berms and concrete and asphaltic concrete (AC} V-channels. Dueto the relatively shallow nature and age ofthe refuse prism at this site, settlement related drainage problems on the deck areas are notanticipated, as discussed in Section 3.4.1. The final cover described in Section 3.3.2 (see Figure 6} will then be placed overthe refuse prism areas. Final slopes ofthe PCFS will be at maximum grades of2.25:1 (horizontal to vertical) (Figure 5}. The final grades have been designed to blend with the natural topography ofthe surrounding area.

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### 3.3 FINAL COVER The purpose ofafinal cover is to provide an effective barrier to infiltration of surface water and to encapsulate wastes, which reduces the potential forvectors, odors, and gas emissions. The cover also provides a base for vegetation, which has been documentedto reduce drainage velocities, erosion and infiltration. 3.3
.1 MINIMUM DESIGN STANDARDS

PCFS FCPCMP The minimum final cover standards for the PCFS are outlined in the closure and post-closure requirements for MSW landfills contained in 40 CFR, Part 258, Subpart F, Section 258.60. The Federal regulations require the following:

• A cover with a permeability less than or equal to the hydraulic conductivity of any bottom liner system or natural sub-soils present, or a permeability no greater than 1 x1

# o-s em/sec, whichever is less. • A cover that minimizes infiltration through a closed landfill by the use ofan infiltration layer that consists ofa minimum 18 inches ofearthen material. • A coverwhich minimizes erosion ofthe final cover bythe use ofan erosion resistant layer that contains a minimum six inches ofearthen material that is capable ofsustaining native plant growth. However, under40 CFR 258.60 (b), an alternative final cover system design may be approved if it is demonstrated that the alternative final cover achieves equivalent reduction in infiltration to the prescriptive standard, and thatthe proposed erosion layer provides equivalent protection from wind and water erosion as the specified prescriptive standard. In addition, the final cover should be designed for minimum maintenance requirements. Grading shall be designed to prevent ponding, providefor slopes ofat least three percent (a lesser slope may be allowed ifsurface drainage is diverted) and minimize surface erosion bywater and wind in areas ofgreater than ten percent slope and in surface drainage courses. Itshould be noted that LEACHM modeling results presented in.a SSFR for the proposed alternative final cover, demonstrates that the proposed alternative final cover provides equivalent protection in infiltration to the prescriptive standard has been prepared. It is being concurrently submitted to the EPA for review and approval as discussed in Section 1.1.
3-2 ]:\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/20103.3.2 FINAL COVER DESIGN Several factors were taken into consideration in determining the cover design for the site to provide for adequate performance ofthe cover. These included the geometry ofthe existing landfill, climatic conditions, potential settlement, available cover materials, erosion protection, vegetative growth and end use at closure. Itwas determined that an alternative final cover design utilizing a monolithic engineered select soil cover is the most appropriate cover system for the PCFS based on these parameters. An engineering analysis (see Appendix D-1) concluded thatthe site-specific climatological and soil conditions supportthe use ofthe proposed alternative final cover design utilizing a monolithic engineered soil. This design will meetor exceed the prescribed performance criteria and will be more economical for site closure than prescriptive standards. Based on the analysis ofthe SSFR in Appendix D-1, an alternative final cover design utilizing a monolithic cover is proposed, consisting ofthe following:

• A four and a halffootthick monolithic cover layer composed ofon-site or near-site soils , which includes a minimum one foot ofwhich has been determined to be in-place (bythe recent existing cover evaluation). • An admixture of pit run rock (clasts greater than six inches will not be used) and soil will be placed in the upper six to eight inches ofthe final coverto provide protection againstwind and water erosion. • A minimum oftwo percent native plant community to be maintained to provide reasonable performance for the ET monolithic alternative cover system. Because the analysis performed to date indicates that afour and a halffoot thick final cover section composed ofon-site or near-site soil material will meetor exceed the performance criteria ofthe prescribed standard, atraditional barrier layer is not proposed for the alternative final cover design. A typical crosssection ofthe proposed alternative final cover system is shown on Figure 6. The alternative final cover configuration has been designed to:

• Ensure the containment ofwaste materials;

PCFS FCPCMP 3-3 J:\lmperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010• Minimize the infiltration ofwaterfrom rain and provide avegetative cover of native shrubs and grasses; • Prevent exposure of people and animals to waste; • Limit landfill gas emissions; • Minimize odor; • Control fires; and • Provide for an aesthetically pleasing appearance. The soil characteristics ofthe site material were identified and evaluated for the PCFS (see Appendix D-1 ). This work included laboratory testing oftwo soil samples from the on-site borrowsources and infiltration modeling. Based on the findings ofthe evaluation, on-site materials meetthe permeability equivalence requirements forfinal cover. Colorado River Basin Regional Water Quality Control Board (RWQCB), USEPA, and the Quechan Tribal Council approval of this design will be sought priorto implementation ofthis alternativefinal cover system. 3.3.3 FINAL COVER CONSTRUCTION

PCFS FCPCMP Clearing and Grubbing Prior to final grading and placement ofthe cover, the deck and slope ofthe landfill will have all existing vegetative materials removed from the foundation surface without disturbing the underlying refuse. All materials generated by the clearing and grubbing operation shall be buried on the upperdeck and covered with one foot ofselect soils from an on-site source. Foundation Layer Foundation layer material will be added in areas ofthe refuse prism which are covered with less than the two-foot minimum ofinterim cover material. It is assumed that the majority ofthe site has an existing one-footthick interim cover in-place. The thickness ofinterim coverwill be verified by pot-holing and additional foundation material placed to meet minimum thickness requirements and to achieve positive gradients for adequate surface water drainage. The entire thickness ofthe foundation layerwill be required to meet90 percent relative compaction according to ASTM 

### 01557.

3-4 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010PCFS FCPCMP Monolithic Select Soil Layer The proposed monolithic layerwill be constructed with select soils obtained from an on-site or near-site source(s), and with the exception ofthe erosion control layer, the monolithic soil layer will exhibit a grain size distribution that excludes particles in excess ofthree inches and includes a minimum fines content ofseven percentfor an individual test and eight percentfor the average often consecutive tests. Prior to placement, these materials will be wetted to optimum moisture and thoroughly mixed to obtain a near uniform condition. The material will then be placed in lifts with a maximum uncompacted thickness ofsix to eight inches. Each liftwill be spread evenly and compacted to a minimum of90 percent of maximum density. Where quality control tests indicate thatthe moisture content, density, permeability or grain size distribution ofany lift, or portion thereof, does not meetthe specifications in Appendix 1 ofAppendix D, that particular portion shall be retested, and if necessary reworked until the specified moisture, density, and permeability has been attained. Special attention will be given to unsaturated material characteristics toverify thatthey satisfy the requirements specified in Appendix 1 ofAppendix D. No additional material will be placed over an area until the previously placed material has been tested and found to meetthe design specifications. Testing ofthe materials will be done in accordance with the CQA Plan included in Appendix 1 ofAppendix D. Erosion Resistant Layer A minimum plant coverage oftwo tofive percentwill provide reasonable performancefor the proposed alternative cover. Vegetation for the proposed alternative cover will consist ofnative plant species. An admixture of pit run rock (clasts smaller than six inches) and soil will be placed in the upper six to eight inches ofthe monolithic cover layer to provide additional protection ofthe final cover system against wind and water erosion. The pit run rock and soil will be obtained from local sources. See the Alternative Final Cover SSFR (Appendix D-1) for a detailed analysis ofthe erosion resistant layer.



### 3-5 ]:\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/20103.3.3.1 ACCESS ROAD Access to the deckarea ofthe PCFS will be provided by an access road. The access road will provide vehicular access to the deck in orderto perform postclosure maintenance and monitoring ofthe final cover and drainagefacilities. 

### 3.4 LANDFILL SETTLEMENT 3.4.1 SEITLEMENTANALYSIS

PCFS FCPCMP This section describes the method ofsettlement analysis used to evaluate the total potential settlementthat may occur during the post-closure period. There are three principal modes of settlementfor a typical municipal waste landfill. These can be described as: consolidation induced settlement resulting from the loss of fluids through drainage, dewatering by absorption, or release of leachate; shrinkage related settlement occurring as a result ofoverall volume loss due to microbial conversion ofsolids and liquids to carbon dioxide and methane gas; and compaction related settlement resulting from the reorientation ofsolids into a more dense configuration (Huitric, 1981). In addition to these "classic" settlement modes, dynamic settlement can occur during and shortly after earthquake events when soil and/or refuse particles consolidate as a result ofground shaking. While it is theoretically possible to calculate the expected settlementfrom each ofthe phenomena described above, the data available forthe PCFS and, in fact, virtually all landfills are insufficientto make a site-specific analysis. Therefore, the analysis for the PCFS is based on historical settlement. Studies performed by Hagerty, Pavoni and Hur (1973) and the Los Angeles County Sanitation Districts (Huitric, 1981)for landfills in the Southern California area indicate that landfill settlements are typically between two and 40 percent oforiginal refuse thickness. The following analysis assumed a 20 percenttotal settlement occurring logarithmically over an approximately 30-year period. Given the extremely dry climate atthe landfill, these assumptions are considered conservative. The first step in the analysis ofsettlement atthis site involved an evaluation ofthe total anticipated depth of refuse at closure. Several points on the site were taken and avertical refuse placement history estimated by taking the total depth of 3-6 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010

### 3.4.1.1 refuse disposed. For example the deepest pointofwaste is estimated at 50 feet. A relatively uniform refuse placement rate overthe life ofthe site was then assumed. The theoretical settlement, which has already occurred at a given node in the refuse prism, was subtracted from the total anticipated for that nodeto generate an estimate ofthe remaining settlement potential. For example, the deepest pointofwaste will experience approximately 10 feet ofsettlement (20% of50 feet) over a 30 year period. Because the landfill has been in operation since 1977, the analysis assumes that 50% ofthe settlementwill have already occurred atclosure and approximately 5 feet ofsettlement during the post-closure period has been calculated atthe deepest pointofwaste. SETILEMENT DUETO UNDERLYING NATIVE MATERIAL SUBSIDENCE The potential for settlement dueto subsidence ofthe underlying natural geologic materials at the PCFS was also evaluated. However, given that the in-place density ofthe refuse atthe site was estimated to be less than that ofthe natural soil excavated from the fill area, and considering that the depth of refuse atthe site is shallow, settlement dueto subsidence ofthe underlying natural geologic materials is notanticipated. 

### 3.5 CLOSED LANDFILL STABILITY

PCFS FCPCMP In accordance with 40 CFR, Part 258, Subpart F, precautions should be taken to maintain the integrity and effectiveness ofthe final cover. Accordingly, landfill cover stability for the PCFS was analyzed. The project plans prepared by BAS (12/2007) were analyzed by Geologic Associates for the proposed closure/post-closure plan. Consistentwith the plan, the site is proposed to have a 4-1/2 foot thick soil final cover overthe refuse mass (BAS, 2007) consistentwith the Final Closure/Post-Closure Maintenance Plan (FCPCMP) for the Landfill. The results ofthese analyses are provided later in this section. The soil materials atthe site include municipal solid waste (MSW) fill below proposed compacted cover/fill materials. No liners or geotextiles are proposed for the cover in the closure plan. 

### 3-7 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010PCFS FCPCMP Geotechnical parameters required for analysis include unitweight and shear strength parameters (angle offriction and cohesion). For the compacted cover soils, which are predominantly cohesionless in nature, the angle offriction and unitweightwere based on average values obtained from laboratory testing of the borrow soils. Three samples 

### (B-1, B-2, and 

### B-3) were obtained from the borrow area south ofthe existing landfill (in the approximate location presented in Figure 1.1 in Appendix I) and transported to our laboratory for geotechnical testing. The samples were tested for gradation analysis (ASTM 

### 0422), maximum density (ASTM 

### 01557), and direct shear testing (ASTM 

### 03080). The samples tested for directshear were remolded in the laboratory to 90% ofthe soil maximum dry density near optimum moisture content. The results ofthe direct shear testing are presented in Appendix I and summarized below. Parameters for the refuse or municipal solid waste (MSW) are based on industry-wide typical values from previously published information (Singh and Murphy, 1990). A summary ofthe parameters used in the slope stability analyses is presented below. Geotechnical Materials Strenl th Parameters Material UnitWeight Friction Angle Cohesion (pcf) (degrees) (psf) Compacted Cover/Fill Soils 

### 118 30 125 Refuse (MSW) 

### 80 30 200 Conventional static and pseudo-static stability analyses forfill slopes were performed using the SLOPE/W (GeoStudio, 

### 2007) computer program. Analytical methods used for analysis included the Morgenstern-Price methodfor circular failure modes. The program calculates the factor-of-safety for a user-specified geometry using a numberofanalytical methods for limit equilibrium. The cover soils were modeled using a representative cross section constructed along the western end ofthe landfill in the area ofthe maximum slope height 

### (25 feet) above the proposed adjacent basin. The cover sols were modeled with a thickness of

### 4-1/2 feet above the existing refuse with a slope inclination of

### 2.25:1 (horizontal to vertical). Stability calculations were performed to evaluate the static and dynamic stability ofthe final (post-closure) configuration ofthe cover. Refuse prism 

### 3-8 ):\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010PCFS FCPCMP configurations, past landfill history, and proposed closure plans were provided by BAS. Based on the above material parameters, the cross section was analyzed for static slope stability. Groundwater is assumed to be belowthe base ofthe refuse and thus, is not significant in this analysis. The results ofthe static slope stability run is presented in Figure 1.2 in Appendix I and is summarized in the following Table. 

### Static Slope StabilityAnalysis Description ofAnalysis Factor ofSafety Static Slope Stability Analysis 2.1 The static cover stability for the maximum height cross section indicates a minimum factor ofsafety of2.1 (which is well above the minimum required static factor ofsafety of 1.5). CCR Title 27 requires the cover slope stability under pseudo-static (dynamic) conditions demonstrate afactor ofsafety greater than 1.5 under the Maximum Probable Earthquake (MPE) for Class Ill facilities. Accordingly, a seismic hazard assessment was performed for the facility to determine the MPE eventfor the site. The site acceleration was calculated by performing adeterministic seismic hazard analysis using the Maximum Probable Earthquake (MPE) on the closest active to the site. This analysis was performed using the computer program EQFAULT (Blake, 2000a) presented in Appendix 

### I. The results ofthis analysis indicate a site horizontal acceleration of0.09gfrom the design earthquake on the Imperial Fault located approximately40 miles from the site. In addition, historic earthquakes were searched using the computer program EQSEARCH (Blake, 2000b) to insure thatthere were no possible historic earthquakes greater than the deterministic deign earthquake. Review ofthe database indicates that the 1852 earthquake with a magnitude of6.3 at adistance of26.6 miles from the site has a calculated site acceleration of0.11 g. Accordingly, our design site acceleration is 0.11 gfor this analysis. The pseudo-static stability ofthe cover is belowthe required stability of 1.5 Therefore, for the proposed closure project, seismic-induced permanent

3-9 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010displacements dueto the MPE were estimated using procedures described by Bray et. al., (1998) and Bray and Rathje (1998). The procedure is based on the methods described by Newmark (1965) for determining displacement ofa rigid block resting on a sliding plane subjected to earthquake-type motions. The procedure is based on the premise thatthe sliding blockwill undergo displacementonly during the periods when the maximum ground acceleration (kmax) exceeds the yield acceleration (ky) for the sliding block, (i.e. displacements occurwhen kv is greater than kmaJ The representative cross section was analyzed to determine the yield acceleration (ky) to achieve a pseudo-static factor ofsafety equal to 1.0. The results are presented in Figure L.3 in Appendix I and indicate ayield acceleration of0.39g. Accordingly, since the calculated horizontal site acceleration due to the MPE event (0.11 g) is significantly less than the yield acceleration (0.39g) to initiate any displacement, the calculated permanentseismic displacement due to the design earthquake event is negligible. 

### 3.6 

### CONSTRUCTION QUALITYASSURANCE

PCFS FCPCMPThe construction ofthe final cover system shall be carried out in accordancewith a CQA plan certified by an appropriately registered engineer or a certified engineering geologist. The CQA plan will provide evidence that suitable materials and standard construction practices are used to place the final cover system and to documentthat placement is consistentwith the closure plan design specifications. Elements ofthe CQA Plan include: projectdescription and definitions, qualifications and responsibilities, requirements for the final cover evaluation, inspection standards, testing frequencies, monitoring procedures, and documentation. The CQA plan is included in Appendix 1 ofAppendix D. It should be noted thatthe CQA Plan addresses all ofthe general guidelines in the InterstateTechnology and Regulatory Council (ITRC) 2003 guidance document. The CQA Plan has been developed to describethe methods and procedures to be used to install the final cover as specified in 40 CFR 258.60. A final CQA Plan will be developed once the final cover design has been approved. The final CQA Plan will provide a detailed methodologyfor determiningfor determining existing cover soil thickness, processing these materials, integrating the final cover soils intothe final cover, and the CQA testing required to demonstrate that appropriate material types and construction practices were used. 3-10 J:\lmperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010

### 3.7 

### DRAINAGE AND EROSION CONTROL 3.7.1 DRAINAGE DESIGN

3.7.1.1

3.7.1.2

PCFS FCPCMPThe primaryfunctions ofthe PCFS drainage control system is to collect and convey stormwater in a controlled manner to minimize erosion ofthe final cover and inhibit infiltration ofstormwater into the refuse prism in orderto maintain the integrity and effectiveness ofthe final cover in accordance with 40 CFR 258. The final surface or deck area ofthe landfill will be sloped to prevent ponding and promote lateral runoffofstormwater, which falls directly on the landfill. The following sections describe the existing drainage control features and the proposed drainage design for closure ofthe PCFS. SURFACE WATER HYDROLOGY A hydrology studyfor proposed conditions atthe site was conducted based on a designed 100-year/24-hour storm, which is more conservative than the Federal regulations for a 25-year/24-hour storm. The objective ofthe hydrology study was to calculate stormwater run-offfor sizing and location information for the site's storm drain facilities at closure. The Rational Method was used for the calculation ofthe peak discharge ofa 24- hour, 100-year storm event. Estimated runoffvalues were calculated based on the National Oceanicand Atmospheric Administration Atlas PrecipitationFrequency Maps. A computer program developed byAdvanced Engineering Software was used to compute the run-off. The hydrology study map for on-site flows and a summary ofthe peak discharge rates is shown on Figure 8. The Hydrology Study calculations are presented in Appendix E. EXISTING DRAINAGE SYSTEM There are no improved drainage facilities currently existing on the site. Surface waterflows follow existing natural contours in several directions and finally discharge into a major natural drainage course, which flows in a southeasterly direction.

3-11 ]:\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/20103.7.1.3 PROPOSED FINAL DRAINAGE CONTROL SYSTEM The final drainage design is shown on Figure 5. Top deck earthen berms, which will contain an admixture ofpit run rock and soil in the upper six to eight inches for erosion protection, shall be constructed to direct run-offaway from the slope area. Collected run-offfrom the deck area will be directed into two discharge points located atthe south and southwest portions ofthe landfill and into two proposed basins. This discharge pointshall be protected with a concrete Vchannel and energy dissipating structure to minimize erosion. All run-offfrom the site will be intercepted by an asphaltic concrete (AC) V-channel and directed to the proposed basin on the southwest side ofthe site. Infiltration rates for arid areas are extremely high and any stormwater, which falls directly into the pits, will be negligible and will evaporate or infiltrate into the ground rapidly. The sizing ofthe concrete and AC V-channels are presented in Appendix E. 3.7.2 SOIL LOSS ANALYSIS

PCFS FCPCMP The Revised Universal Soil Loss Equation (RUSLE) was used to evaluate potential soil losses within the watershed boundary ofthe PCFS site. The RUSLE, developed bythe U.S. Department ofAgriculture, considers soil and vegetation type as well as physical and climaticfeatures ofthe landfill area. The RUSLE is: where 

### A A 

### R 

### K L 

# s c p 

## = = RKLSCP average annual soil loss, in tons/acre/year rainfall and runofferosivity index soil erodibilityfactor, tons/acre slope-length factor slope-steepness factor cover-managementfactor practice factor The soil loss analysis performed is based on a "closed landfill" condition. At closure, the potential soil loss is minimal since the landfill will have a compacted final cover with six to eight inches ofa pit run rock and soil admixture, vegetation, and a storm drain system installed which all contribute to controlling soil erosion.

3-12 J:\lmperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010The following RUSLE constants were utilized: 

### R 

### =27.0 

### K 

## = 0.06 0.4:SLS:S9.5 

## c =0.05 

### p = 

### 1.0 Located in aType II area Based on 25-50 percent gravel Dependent upon length gradient Based on a monolithic coverwith gravel admixture Practice factor For the purpose ofthe soil loss analysis, the landfill was divided into regions based upon the average slopes ofthe final grades and surface drainage. The landfill soil loss analysis data is presented in Appendix F. The average soil loss for the PCFS is 0.23 tons/acre/year, which is within the two tons/acre/year recommended by the USEPA. Overthe 30-year post-closure maintenance period, the average soil loss overthe entire site would be 0.04 inches. The top layer ofthe final coverwill include atwo and a halffootthick layer ofonsite or near-site soil material thatwill comprise the monolithicvegetative cover layer. In addition, the top six to eight inches ofthis layerwill include an admixture ofpit run rock and soil. According to the Wind Erodibility Indexfrom the USDA, the (I) value forWEZ equation is approximately zero (0) for soils not susceptible to wind erosion or saltation dueto coarse fragments at the surface or wetness. Therefore, the annual soil loss dueto wind erosion is small dueto the coarse soil used. When combined with the soil loss to surface water runoff, the annual soil loss is still less than two tons/acre/year and is therefore adequate for average annual soil loss. 3.7.3 EROSION CONTROL

PCFS FCPCMPThe landfill closure design has two primary erosion control features thatwill reduce the potential for soil erosion due to water and wind. These features include fill area grading and the monolithicvegetative cover, which will include a mixture ofselect soils and pit run rock. The decks will be graded for sheet flow runoffwith a minimum slope ofapproximatelythree percent. Any large erosion gullies formed during storm events on the deck and slopes will be promptlyfilled, and trackwalked by a crawler tractor to recompactthe soil. In addition to pit run rocks, protection ofthe final cover soils will be provided through the placementof non-irrigated, native plant species cover serving as a shortterm and longterm erosion control cover. Approximately two percent of 

### 3-13 ]:\Imperial County\Picacho Ll\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010vegetation needs to be sustained because that is the percentage ofnatural vegetation that is typical in the vicinity ofthis site. The final cover seed mixture is identified in Table 2. All final cover slope and deck areas will be seeded with this mixture. The plants were selected because oftheir adaptability to the landfill's general climatic area; reseeding potential; and required root depth of less than 30 inches. The longterm vegetative maintenance needs are anticipated to be minimum since the plants are tolerantto disease, fire and insects. The plants are also compatible with the off-site native plant community and will provide a similar appearance to the surrounding native open space vegetation
. Itis proposed thatthe final cover be seeded in December, prior to the "wet" season. Seeding will be accomplished by drill seeding. Prior to drill seeding soil preparation/fertilization is performed by spreading the appropriate amendments. The drill seeder is equipped with seed boxes calibrated for the specified seed types, soil discs and a metal orwood rake. As the discs 

### till the soil to a onequarter inch depth, the seed boxes drop the seed directly into the soil. The rake then passes over the loosened soil, which buries the seed. For best soil preparation and drill seeding results the soils should be moistened to a 2-inch depth. 

### 3.8 LANDFILL GAS CONTROL/MIGRATION MONITORING SYSTEM

PCFS FCPCMP In order to ensure detection ofpotential gas migration throughout post-closure, a landfill gas migration monitoring system is proposed for the site. The proposed landfill gas migration monitoring probe plan (Appendix

### J) has incorporated elements from 27 CCR, Section 20925, which is more stringent than the Code of Federal Regulations. There are currently no structures located within 1,000feet ofthe PCFS. Four proposed gas migration monitoringwell locations, with varying depths, will be spaced no more than 1,000feet apart. Based on the depth ofwaste, it has been determined that monitoringwells will have one to three probe depths installed within each monitoringwell. The wells will be constructed to provide a minimum seal offive feet ofbentonite at the surface and between the monitored zones. In addition, each individual probe (i.e., shallow, intermediate, deep) will be clearly marked with the letters "S" for shallow probe or "I" for intermediate probe or "D" fordeep probe to delineate depth
. A typical subsurface monitoring well (probe) is shown on Figure 6.

3-14 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010The landfill gas migration monitoringwells will be installed by a licensed drilling contractor underthe direction ofa design engineer or engineering geologist. The wells shall be logged during installation by a geologist or geotechnical engineer. A final reportwill be prepared incorporating as-built surveyed probes locations, field logs, and daily reports. As presented in Section 2
.1 ofthis document, a landfill gas control system is not necessary for this site. 

### 3.9 

### GROUNDWATER MONITORING SYSTEM As previously discussed in Section 2.2, the existing groundwater monitoring system consists ofone upgradient and three downgradient monitoringwells. Based on historical water elevation data, generally, well P -MW-1 is located upgradient ofthe landfill; well P -MW-4 is located downgradientofthe landfill's pesticide disposal area; wells P -MW-2 and P-DW-3A are located downgradientof the landfill

. With the exception ofwell P-DW-3A, which is used as awater level measuring station, these wells are currently being monitored and/or sampled on a semi-annual basis in accordance with the groundwater sampling and analysis plan included in Appendix 

### C. A proposed groundwater monitoringwell (P-MW5) is anticipated to be located cross-gradient ofthe landfill. Protocols for sampling proposed monitoringwell P-MW-5 are anticipated to followthe same sampling and analysis plan as the existing monitoringwells
. As discussed in Section 1.1, GLA has prepared aSSFR to modify the list of detection monitoring parameters provided in 40 CFR 258.54(a) (1) and (2). This SSFR is included in Appendix C-1. 

### 3.10 LEACHATE COLLECTION AND REMOVAL SYSTEM

PCFS FCPCMPThe PCFS is unlined and predates the requirements for installation ofa liner and LCRS. Additionally, operators ofexisting MSWLF units are exemptfrom Subpart D (i.e., 258.40) of40 CFR undercertain conditions. Section 258.1 (f)(1) allows for existing MSWLF units to be exemptfrom Subpart D, so long as the operator is able to demonstrate that the existing MSWLF unitaccepts less than twenty (20) tons ofMSWdaily, based on an annual average, and there is no evidence of groundwater contamination from the MSWLF unit. CIDPW records indicated that the PCFS received an average of 13 tons per day in 2008 and routine 3-15 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010groundwater monitoringto detectcontaminants is performed according to the schedule in Appendix 

### C. Therefore, the PCFS is exemptfrom the requirements ofSubpart D for installation ofa liner and a LCRS. 

### 3.11 SITE SECURITY In accordancewith 27 CCR, Section 21135, signs will be posted at all points of access to the PCFS 60 days prior to the last receipt ofwaste atthe site and for a period not less than 180 days after the facility has received the final shipment of waste. Signs will state the intended date oflast receipt, the location of alternative solid waste managementfacilities, and a numberto call in cases of emergency. A notice shall be placed in a local newspaper(s) 30 days prior to the last receipt ofwaste, which also includes the intended date ofthe last receipt of waste at the site and the location ofalternative solid waste management facilities. In addition, the operator is required to secure all points ofaccess with a lock and gate and place signs atall access points prohibiting unauthorized entry. These measures are intended to reduce incidents ofvandalism and illegal disposal of wastes during the post-closure maintenance period. In accordance with 27 CCR, Section 21135, all points ofaccess to the site will be restricted as ofthe date ofthe final shipmentofwaste. A sign similar to that presented in Figure 9 will be posted atthe entrance to the PCFS. Site security atthe PCFS is currently provided by a locking gate and chain-link fence around three sides ofthe site (north, south and west sides). For the location ofthe existing perimeterfence and gate, see Figure 

### 2. Additional fencing is proposed to be placed along the entire landfill perimeter in order to prevent unauthorized entry to the site at closure. 

### 3.12 STRUCTURE REMOVAL/DECOMMISSIONING OF ENVIRONMENTAL CONTROL SYSTEMS

PCFS FCPCMP Site structures not deemed essential for closure construction or post-closure maintenancewill be dismantled and removed
. There are currently no permanent structures located atthe PCFS and no structures will remain on-site duringthe post-closure maintenance period. 3-16 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010

### 3.13 3.13.1

PCFS FCPCMP At this time there are no plans to decommission any ofthe environmental control systems at the site during the closure period. Ifdeemed necessary, any groundwater monitoring wells that will not be utilized for monitoring purposes duringthe post-closure period, or that require replacement during ongoing operations, will be abandoned as approved by the appropriate agencies and in accordancewith the Imperial County Building Inspection regulations and the DepartmentofWater Resources Bulletin 74-90. CLOSURE IMPLEMENTATION SCHEDULE CLOSURE PROCESS After approval ofthe Closure Plan, construction plans and specifications will be prepared by the operator and submitted to the Quechan Tribal Council with final regulatory approval made by the USEPA Region 9. Itshould be noted that EPA approval is required for anyvariance from the prescriptive standards as outlined in 40 CFR 258 through the SSFR process. The bidding package will be issued and a contractor selected. A closure implementation schedule for the PCFS is presented in Table 3, which delineates the estimated time frame to complete each closure task described in this FCPCMP. This schedule may differfrom the selected Contractor's schedule based on the Contractor's equipment and personnel resources. Closure construction will begin with mobilization ofequipmentand materials. The type ofequipmentand required personnel expected to be utilized during closure construction includes the following:

• Types of Equipment

- Dozers

- Loaders

- Compactors

- Trucks

- Soil Conditioning (Grizzlies) and Screening Equipment • Personnel

- Equipment Operators

- Surveyors 3-17 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010

### 3.13.2

PCFS FCPCMP - Mechanics Once equipment is on-site, rough grading can begin. During the preparation of the site forfinal cover placement, additional final cover materials may be stockpiled. Necessary borrow material will continue to be transported and stockpiled on-site during construction ofthe final cover, as necessary. Prior to placement offinal cover, the rough grading and final cover keyway installation will be performed which should take approximately one month. Placement ofthe final cover materials will begin after rough grading and drainage improvements atthe site are complete. It is anticipated that construction ofthe final coverwill take approximately one month to complete. The access road/staging area construction will be completed in conjunction with the completion ofthe final cover. The gas migration monitoring system installation will also take place in conjunction with the completion ofthe final cover and should be completed within 15 days. Upon completion ofthe gas migration monitoring system and access road/staging area the landscaping improvements will be performed, which should take approximately one week. Upon completion ofthe tasks described above for closure, demobilization will begin. CONSTRUCTION MANAGEMENT A construction managementteam will be on-site during the entire period of construction. The team will be under the direction ofa construction manager, whowill be responsible for supervision ofconstruction ofthe variousfeatures included in the closure plan. The construction manager will coordinate the activities ofthe on-site contractors and will provide liaison among the design engineers and the contractor(s). Other key staffwill include a site engineer, who is a County staff representative, and construction inspector(s). A survey crew and a geotechnical CQA crewwill be present, as required. Survey Control The survey control crew, underthe direction ofthe contractorwill be responsible for location ofthe closure plan improvements and for record drawing information. Theywill be responsible for establishing thatthe various components ofthe cover conform to grade and/orthickness requirements ofthe construction drawings and specifications. 

### 3-18 ):\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010PCFS FCPCMP CQAfor Final Cover Placement The construction specifications will include the CQA plan for cover placement. A geotechnical CQA crew, underthe direction ofa Geotechnical Engineer, will be on-site full time during the placement ofthe final cover to monitor compliancewith cover design and installation methods included in the CQA plan. The CQA personnel will have day-to-day responsibility to oversee cover placementand to evaluate whetherthe cover is constructed according to specifications. As described in Section 3.6, the CQA Plan is included in Appendix 1 ofAppendix D. It should be noted that the CQA Plan addresses all ofthe general guidelines in the InterstateTechnology and Regulatory Council (ITRC) 2003 guidance document. The CQA Plan has been developed to describe the methods and procedures to be used to install the final cover as specified in 40 CFR 258.60.



### 3-19 J:\lmperial County\Picacho Lt\2010.0044 Fcpmp\Reports\Picsec3.Doc; 10/21/2010

## SECTION 4.0 POST-CLOSURE MAINTENANCE PLAN

BRYAN A. STIRRAT & ASSOCIATES

## 4.0 POST-CLOSURE MAINTENANCE PLAN

4.1 INTRODUCTION Post-closure maintenance ofthe closed PCFS will be performed in accordance with the applicable regulatory standards presented 40 CFR Section 258.61. Pos tclosure maintenance activities for the PCFS will consist of:

• Landfill Gas Migration Control System Monitoring and Maintenance • Groundwater/Vadose Zone Monitoring and Maintenance • Stormwater Monitoring • Final Cover Inspection and Maintenance • Settlement Monitoring • Vegetative Cover Inspection and Maintenance • Access Road Maintenance • Drainage Control System Inspection and Maintenance • Site Security Inspection and Maintenance The following subsections will discuss compliance with 40 CFR 258, as applicable
. Post-closure care requirements will be conducted in accordance with 40 CFR 258.61. Post-closure care must be conducted for 30years with the exception where the duration may be decreased in accordance with 40 CFR 258.61(b)(1) or increased in accordance with 40 CFR 258.61 (b)(2) with approval by the USEPA and is deemed a sufficient duration to protect human health and the environment. 

### 4.2 RESPONSIBLE PARTIES

PCFS FCPCMPThe following is a listing ofthe responsible parties who will be involved in postclosure maintenance and monitoring activities atthe PCFS. Questions pertaining to this Final Post-Closure Maintenance Plan should be directed to the CIDPW Project Engineer for the PCFS

.



### 4-1 ]:\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010Landfill Owner Quechan Indian Tribe Council P.O. Box 1899 Yuma, Arizona 85366-1899 (602) 572-2102 Landfill Operator County of Imperial Departmentof Public Works 155 South 11th Street El Centro, California 92243 William Brunet, Director of Public Works Frank Fiorenza, Deputy Directorof Public Works (760) 482-4462 Prior to any transfer ofownership during the closure or post-closure maintenance period, responsible parties shall inform the newowner ofcurrent regulations, conditions, and agreements assigned to assure compliance. Additionally, the responsible parties will be responsible of notifyingthe LEA regarding title change within 30 days providing name, firm, mailing address, and telephone number of the new owner. The CIDPW, as the landfill operator, will be responsible for post-closure personnel (maintenance and monitoring), the Site Engineer, and other postclosure contractors. 

### 4.3 LANDFILL GAS MIGRATION MONITORING AND MAINTENANCE The proposed landfill gas migration monitoring system program described in this section provides the methods and procedures required to detect migrating landfill gas. The proposed monitoringwells will be installed around the perimeter ofthe landfill as part ofclosure construction (see Appendix

### J). 4.3.1 LANDFILL GAS MIGRATION MONITORING PROCEDURES

PCFS FCPCMP Monitoring procedures for the gas migration monitoring system will include inspection ofthe subsurface monitoringwells for verification ofproper operation. All probes will be monitoredfor methane to ensure thatthe concentration does notexceed 25 percentofthe lowerexplosive limit (LEL) in facility structures 4-2 ]:\Imperial County\Picacho Lt \2010.0044 Fcpmp\Reports\Picsec4.Doc; 10 /21/2010(excluding gas control or recovery system components) orthe 

### LEL for methane at the facility property boundary. The monitoring events shall be conducted on a quarterly basis, at a minimum in accordance with 40 CFR 258.23(b}(2}. This monitoring program has been determined based on the criteria specified in 40 CFR 258.23(b}(1}. 4.3.2 LANDFILL GAS MIGRATION MONITORING REPORTING The results ofthe gas migration monitoring program will be submitted to the USEPA, the Quechan Tribal Council within 90 days ofsampling unless compliance levels are exceeded. The results will include the concentration of total hydrocarbons in each probe along with information involving personnel and general conditions in which the sample was obtained. Should the compliance levels be exceeded, immediate necessary steps will be taken to ensure protection of human health and notification ofthe USEPA and Quechan Tribal Council will occur. Within seven days ofdetection ofan exceedance, the methane gas levels and a description ofcorrective action will be placed in the operating record in accordancewith 40 CFR 258.23(c). Within 60 days ofdetection, a remediation plan for the control ofmethane gas releases will be implemented. A copy ofthe remediation plan will be placed in the operating record and the USEPA and QuechanTribal Council will be notified that the plan has been implemented. The plan will describe the nature and extent ofthe problem and proposed follow-up actions in accordance with 40 CFR 258.23(c}(3}. Itshould be noted thatthe USEPA may develop an alternative schedule for demonstrating compliance with 40 CFR 258.23(c}(2} and (c}(3}. 4.3.3 MAINTENANCE OF LANDFILL GAS MIGRATION MONITORING SYSTEM

PCFS FCPCMPThe general maintenance requirements for the gas migration monitoring system are limited to replacing broken valves and fittings. As previously discussed, gas probes will be inspected at the time of monitoringfor proper operation. Any deficiencies will be corrected immediately. The following equipmentwill be utilized, as needed, for maintenance, repair or replacement ofprobes forthe gas migration monitoringsystem:

4-3 ):\Imperial County\Picacho Lf\2010.0044Fcpmp\Reports\Picsec4.Doc; 10/21/2010• Various hand tools including hand saws, pipe cutters, electric drills, pipe taps, wrenches, hammers, hand orelectric pump and/orshovels. • Backhoe. Equipmentwhich may be needed to perform probe installations:

• Drill Rig. • Frontend loader. • Dump truck. • Drillers maintenance truck. • Various hand tools needed to perform work including: shovels, generator, temporary support blocks. • Safety equipment including: hard hat, goggles, gloves, steel toe rubber boots, overalls, safety beltand respirator. • Additional equipment may also be needed due to certain environmental conditions, as required, in the site safety plan. Materials

• PVC pipe • Compression fittings • Threaded pipe caps • PVC labcockvalves • Teflon tape 

### 4.4 GROUNDWATER, LEACHATEAND SURFACE WATER MONITORING

PCFS FCPCMPThe purpose ofthe monitoring program discussed in this section is to detectany migration ofcontaminants to the groundwaterfrom the closed waste disposal area. Initially, because California is a U.S. EPA-approved State regulating solid waste facilities within the State, the site was thoughttofall under thejurisdiction ofthe California Regional Water Quality Control Board - Colorado River Basin Region, and site monitoringwas performed in accordance with site-specific Waste Discharge Requirement No. 88-005, and the more recent blanketWaste Discharge Requirements No. 93-071, established for all active landfills within the Colorado River Basin Region and prepared to complywith federal regulations. As a result, the groundwater monitoring program for the site has been performed


### 4-4 ):\Imperial County\Picacho Lt\2010.0044Fcpmp\Reports\Picsec4.Doc; 10 /21/2010in accordance with the groundwater sampling and analysis plan (included in Appendix 

### C) and these WDRs. However, the site is located on Tribal land, and therefore, itis subjectto federal regulations. To fully complywith federal regulations, an SSFR was prepared requesting a modification to the list of detection monitoring parameters provided in 40 CFR Part 258.54(a)(1) and (2) (Appendix C-1). There are no surface water bodies at or near the site. The Picacho wash, which passes along the eastern side ofthe property, rarely contains surface water, exceptfor short periods oftime immediately after a significant rain event. As discussed in Section 2.2, the CIDPW is currentlyworking on submitting a Notice of Intent (NOI) underthe Multi-Sector General Permit and developing a Stormwater Pollution Prevention Plan (SWPPP) and Stormwater Monitoring Plan (SWMP) for the PCFS. The PCFS site does not have nor is required to install a leachate collection and removal system, therefore, no leachate monitoring or maintenance procedures are discussed herein. 4.4.1 GROUNDWATER MONITORING PROCEDURES

PCFS FCPCMPCIDPW monitoring personnel (or its subcontractors) will conductthe groundwater monitoring program described in Appendix C during the entire post-closure period. It is expected that modifications to program frequency and protocolswill take place, depending upon changing conditions, results of monitoring and advancing technology. This plan will be amended to include any changes in the monitoring program or modifications to the system including any proposed remediation systems. The existing groundwater monitoring system at the PCFS consists ofthree monitoringwells (P-MW-1, 2, and 4) and onewater level measuring station (PDW-3A). One additional groundwater monitoringwell (P-MW-5) is proposed as part ofclosure. All ofthe groundwater monitoringwells are being monitored in accordance with site specific WDR No. 88-005, and blanketWDR Order No. 93- 071, which were established bythe Colorado River Basin RWQCB for all active landfills within the Colorado River Basin Region. Because the site is located on Tribal land, federal regulations administered bythe U.S. EPA govern the site 4-5 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010program. Therefore, a SSFR has been prepared recommending a modified the list ofdetection monitoring parameters from those listed within 40 CFR 258.54(a) and generally consistentwith the current monitoring program. The current groundwater sampling and analysis program is included in Appendix 

### C. All groundwater samples will be analyzed for routine monitoring parameters including chloride, nitrate as nitrogen, pH, sulfate, total dissolved solids, arsenic, and the 40 CFR 258Appendix I list ofvolatile organic compounds (VOCs) as outlined in the groundwater sampling and analysis plan included in Appendix C on a semi-annual basis. The lowest possible analytical detection limits will be used so thatthe method detection limits are below currently established regulatory MCLs. In addition, the groundwater monitoringwells are analyzed for the full suite ofCOCs listed in Appendix II of40 CFR, Part 258. COC sampling was last performed at the PCFS in August 2006. Following construction ofwell P-MW-5, samples from this well will be analyzed for the entire Appendix I listof monitoring parameters includingthe 15 metals as specified in 40 CFR 258, for two semiannual monitoring periods before routine sample analyses are performed at this well. 4.4.2 GROUNDWATER MONITORING EVALUATION AND REPORTING

PCFS FCPCMPAfter data are received from the laboratory, the datawill be qualitatively evaluated priorto performing statistical analyses. The datawill be evaluated by reviewing the quality control information that is included with the laboratory report. The quality control information provided bythe laboratorywill include measures ofaccuracy, precision, and sample contamination. The quality control information will be reviewed to determine that the qualitycontrol measures such as percent recovery and relative percent difference are within acceptable ranges, as determined by the laboratory. Ifthese measures are outside the acceptable range, the laboratorywill be asked to provide written documentation to explain the cause or potential cause forthe failure to meet the quality control acceptance criteria. Ifthe quality control acceptance criteria are not met, then the associated laboratory results are questionable and will not be included as partofthe statistical analysis. Immediate resampling ofthe wells will not be performed unless the analysis for VOCs is deemed invalid. Otherwise, samples will be collected duringthe following scheduled semiannual sampling event.

4-6 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010PCFS FCPCMPThe laboratory data, particularly inorganic parameters, will also be reviewed for outliers and anomalies. Outliers and anomalies are unusually or inconsistently large or small values that may be influenced by sampling, laboratory, shipping, or transcription errors. To date, sufficient historical databases for each well and analyte have been assembled so that data anomalies or outliers can be identified using statistical or comparative methods. Ifadditional wells or analytes are added to the routine groundwater monitoring program, a minimum ofeight measurements will be required before analysis ofoutliers or data anomalies can be conducted. To assist in detecting outliers, time-series charts ofanalyte concentrations will be produced for each constituentfor each well. Ifa significant trend or an anomalously high result is observed, then field and laboratory procedures will be evaluated. Ifthe source ofan error cannot be determined and the laboratory results from the subsequent sampling event provide similar results, then the data will be considered reliable and be used for statistical analysis. Ifthe laboratory results from the subsequent sampling event do notverify the previous data, even ifthe source oferror cannot be determined, then the outlier oranomalous sample pointwill be removed from the database for the purpose ofstatistical evaluation. Statistical Methodology The recommended statistical method to be employed is by prediction interval, intra-well comparison, which compares the groundwater chemistry data collected from each individual well through time. This is considered appropriate because ofthe shallow site gradient, which results in some seasonal variability in the designation ofupgradient and downgradientwells, the extensive databases for each well (at least 20 discrete sampling events), and generally similar upgradientand downgradient groundwaterchemistries. Underthis method acorrelation equation is calculated for each well and each analyte forwhich there are at least eight data points, based on the historical data, and a "normal" range ofvalues is predicted for the following monitoring period. Ifthe value ofthe last sampling period is inconsistentwith the historical data trend, then contamination is suspected. This method is consistentwith the statistical technique ofprediction intervals recommended by the 40 CFR 

### 258.53(g).

4-7 ):\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010PCFS FCPCMPFor organic compounds (VOCs, pesticides, etc.), alaboratory-specific Practical Quantitation Limit (PQL) will be used as its statistical concentration limit. Because the calculation ofthe laboratory-specific PQLs incorporates a measure ofstatistical uncertainty associated with the measurement process, any detected organic compound that is verified at a concentration above the PQL is statistically significant. Laboratory-specific PQLs will be periodically recalculated in accordance with 40 CFR, Part 136, or equivalent. Iforganic compounds are found and verified in samples from awell, statistical methods as described in the following section will be used. Detection Verification Procedure Ifone or more compounds are detected at concentrations in excess ofthe appropriate statistical limitas described above, then verification samplingwill be performed. The schedule ofverification samplingwill be as follows: Organic Compounds: Ifone or more compounds is detected above the PQL, verification sampling will be immediately scheduled for collection from the well that produced the original significant detection. Inorganic Constituents: Ifone or more inorganic compounds is detected at above its respective statistical limit, then verification sampling will occur during the next regularly scheduled sampling event. Ifthe laboratory results ofthe verification samples confirm thatthe concentrations ofthe subject compounds are above their statistical limits, then the _US EPA- Region 9 will be notified and assessment monitoring in accordance with 40 CFR 258.55 will begin. Trend Analyses Analysis ofgroundwater quality data trends will be performed as an annual reporting requirementforthe PCFS in supportofthe semiannual intrawell statistical analyses. Trend analyses will be performed by plottingthe concentrations ofa groundwateranalyte over five years orthe period oftime that awell has been sampled whichever is less. Time-series charts will be prepared for each well or analyte and the historical data will also be compared with Federal maximum contaminant levels (MCLs), as appropriate. For the VOCs, and otherorganic compounds, charts will be prepared for each VOC that 4-8 !:\Imperial County\Picacho Lt\2010.0044Fcpmp\Reports\Picsec4.Doc; 10/21/2010PCFS FCPCMP has been regularly detected at least 10 percent ofthe time in samples from at least one monitoringwell. Significant increasing trends in laboratory measured analyte will be used as away ofassessing changes in the groundwater chemistry indicative of release from the landfill. Assessment Monitoring When one or more detection monitoring parameters is measured at a statistically significant concentration, in accordance with 40 CFR 258.55, assessment monitoringwill begin. Atthe onset ofan assessment monitoring program, groundwater samples will be collected and analyzed within 90 days for all ofthe parameters listed in Appendix II of40 CFR, Part 258 and annually thereafter. The USEPA may specify an alternate frequency for the repeated sampling and analysis ofthe full assessment monitoring parameters. The USEPA may also specify an appropriate subset ofwells to be sampled and analyzed during assessment monitoring. After a minimum offour sample sets ofthe detected assessment monitoring parameters have been analyzed, background concentrations and groundwater protection standards will be established for the detected assessment monitoring parameters. Ifthe concentrations ofall assessment monitoring parameters are shown to be at or below background concentrations for two consecutive sampling events, the USEPA will be notified, and assessment monitoringwill end, and detection monitoringwill resume. Ifthe concentrations ofany ofthe assessment monitoring parameters are detected at statistically significant concentrations above the background concentrations but below the groundwater protection standards, then assessment monitoringwill continue. Ifthe concentration ofan assessment monitoring parameter is detected at a statistically significant concentration above both the background concentration and groundwater protection standard, then the USEPA will be notified within 14 days. The nature and extent ofthe contamination will be characterized with the installation ofat least one additional monitoringwell atthe facility boundary in the direction ofcontaminant migration, in accordance with 40CFR 258.55(g)1(ii). Persons who own land or reside on land that directly overlies any partofthe contamination plumewill be notified. Also, an assessment ofcorrective measures will be initiated within 90 days offinding that an assessment monitoring parameter is above background concentration and the groundwater 4-9 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010protection standard. Assessment monitoringwill continue duringthe assessment ofcorrective action phase. A demonstration thatthe source ofcontamination other than the landfill caused the contamination detected during the course ofgroundwater monitoring, or that the statistically significant increase resulted from an error in sampling, analysis, statistical evaluation, or natural variation in groundwaterquality, may be submitted for review and approval by the USEPA. Ifa successful demonstration is made, then assessment monitoring may continue, though assessment of corrective action will not be pursued. Semi-annual monitoring reports will be prepared in accordance with the site's groundwater monitoring program and WDRs. The reports will be submitted to the USEPA- Region 9 and the Tribal Council. Every five years, the results ofthe COC testingwill be incorporated into the semi-annual monitoring report. 4.4.3 GROUNDWATER MONITORING SYSTEMS MAINTENANCE

PCFS FCPCMPThe groundwater monitoringwells must be serviced and maintained to allow the wells to perform to the proper standards for which theywere designed. Monitoringwells will be inspected at least semi-annually during sampling to determine ifthe well has been tampered with or damaged and toverify that the well cover is secure. Ifwell damage is observed or ifsampling equipmentcannot be used to collecta sample, the condition will be noted and CIDPWwill be informed ofthe nature and extent ofcorrective action. All necessary maintenance and/or repairs forwells will be documented using the sample Form C included in Appendix G. In the eventthat awell may need to be replaced, aCalifornia licensed driller is recommended to be used to drill and construct any replacement well. The replacementwell is recommended to be designed by a California registered geologist (RG) or professional engineer (PE) in accordance with "California DepartmentofWater Resources" (DWR Bulletin 74-90). All drilling and well construction activities are recommended to be underthe directsupervision ofan RG or PE. Notethatthe California DepartmentofWater Resources does not have authority overthe PCFS, which is located on land governed bythe Quechan Tribal Council.

4-10 j:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010Ifa groundwater monitoring well becomes unusable or unrepairable, it is recommended that the well be abandoned following RWQCB procedures in accordancewith "CaliforniaWell Standards: California DepartmentofWater Resources" (DWR Bulletin 74-90). Well repairs, which typically includewell development, are considered CIDPW projects and as a result, they will go outto bid to qualified contractors. The bid preparation and selection process, mobilization, and well repair will typically require approximatelythree to six months to complete. Itshould be noted that the Site Engineer will be employed by either CIDPW or an outside contractor, whowill report directlyto the Director ofthe Departmentof Public Works. 

### 4.5 

### FINAL COVER INSPECTION AND MAINTENANCE

PCFS FCPCMP Post-closure care ofthe final coverwill be maintained and repaired, as needed, in accordancewith 40 CFR 258.61(a)(1 ). The purpose ofthe completed final cover is to:

• Minimize storm water infiltration into and through the closed landfill, • Minimizethe venting ofgas generated in the facility, • Isolate the buried wastes from the surface, • Promote drainage, • Minimize erosion or abrasion ofthe cover, and • Accommodate settlement and subsidence so that cover integrity is maintained. The primary purpose ofthe final cover maintenance procedures is to maintain the integrity ofthe completed final cover overthe long-term and provide maintenance, scheduling and documentation so that materials and maintenance practices are consistentwith the final cover design specifications. Quarterly visual inspections ofthe final coverwill include identification ofany erosion and settlement problems and slope stability issues. The Site Engineer will be responsible for documenting the location and extent ofany repairs. As indicated in Section 

### 4.4.3, the Site Engineer will be employed by either CIDPW oran outside contractor, who will report directly to the Directorofthe Departmentof PublicWorks.

4-11 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/20104.5.1 PERIODIC LEAK SEARCH/IDENTIFICATION OF PROBLEM AREAS All employees with access to the site will be instructed to report anyfinal cover surface cracking, ponding or unusual surface conditions to the Site Engineer, who will record the information in the site logbook at the time they are observed. Scheduled, formal inspections will be performed on a quarterly basis by grid walking the site tovisually observe the following:
• Evidence oferosion • Visible depressions • Ponded water • Odor • Exposed refuse • Cracks • Settlementand subsidence • Slope failure • Leachate seeps In addition to routine inspections, the site will be inspected following any major storm event, seismic event, or natural disaster. The drainage control facilities will also be inspected quarterlyfor improperoperation and resultant effects on the surroundingfinal cover. A formal report offindings is to be presented to the Site Engineer. 4.5.2 MAINTENANCE PROCEDURES

PCFS FCPCMPThe proposed final cover designed forthe PCFS consists ofatwo-footthick foundation layer composed ofselect soil materials, a minimum one foot ofwhich has been determined to be in-place bythe recent existing cover evaluation and a two and a halffootthick layer ofon-site or near-site soil material thatwill comprise the monolithicvegetative cover layer (Figure 6). All final cover repair and/or reconstruction activities shall be conducted in a manner directed to maintain the integrity ofthe as-built final cover system. Repair offill materials should be performed in six to eight inch layers and procedures utilized during the original final cover construction. Any repair ofthe final coverwill require removal ofthe pit run rock and soil surface. The rock surface should be scraped from the area requiring repair and stockpiled for

4-12 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010PCFS FCPCMPplacement upon completion ofthe repair. The following methods ofrepair are recommended for the following two modes offinal cover distress:
• Settlement related sags and drainage interruptions, which interferewith the controlled flow and discharge ofsurface waters from the closed landfill surface. • Surface erosion as a result ofdrainage channel"overflow" associated with intense rains. Final cover repair activities will be conducted and documented as specified in the CQA Plan. Sags, Ponds, Drainage Interruptions and Surface Erosion Any minor repair ofdepressions in the final cover shall be completed in the landfill area on an annual basis immediately prior to the rainy season (October 15 to April 15). Ifsignificant sags or ponds are identified during other times of theyear, the Site Engineer shall accurately locate the limits ofthe depressions both horizontally and vertically and required repairs shall be completed as soon as possible. A channel capable ofdraining the lowest pointofthe sag will be constructed or additional soils will be placed such thatthe intended flow ofsurface water is unimpeded. The Site Engineer will be responsible for fill placement occurring only in the area ofthe sag; only thatfill which is necessary to facilitate drainage is placed; and that sufficient record ofthe depths and limits offill placementare kept. The depth and limit records should always be available so thatthe appropriate area can be re-excavated and permanently repaired during the annual maintenance period, ifnecessary, as discussed below
. The permanent repair ofsags and ponds, when necessary, will be performed by excavating to the undisturbed soils and adding any select soil material necessary to maintain a positive gradientand rebuilding to at leasttwo percent gradient, if possible. In areas ofdrainage interception and surface erosion, reconstruction will be consistentwith the materials and practices utilized during closure construction. All records ofcover repair will be kept in the record library
. A certified engineering geologistwill inspect and certify repairs to the final cover layer.



### 4-13 ):\Imperial County\Picacho U \2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010

### 4.6 LANDFILL SETTLEMENT MONITORING Settlement monitoring every five years is adequate at PCFS due to the following factors: 1) settlement is expected to be relatively slow based on the arid climate and the shallow depth of refuse and related low overburden pressure; and 2) the systems, which can be affected by differential settlement (i.e., final cover and drainage control), will be inspected on a much morefrequent basis than every five years so potential issues will be identified without more frequent settlement monitoring. Ifthe regulatory agency(ies) determine thatthe frequency should occur more often, then the initial monitoringwill be conducted on a bi-annual basis with a reduction in frequency to every five years, ifsubstantiated by the results ofthe first two monitoring events. 

### 4.7 

### ACCESS ROAD MAINTENANCE The site access road will be inspected duringthefinal cover inspection on a quarterly basis for cracks and pot holes. Ifany large cracks or pot holes large enough to collectwater are noted, the affected area will be repaired in accordance with the final cover repair procedures discussed in Section 4.5.2. 

### 4.8 DRAINAGE SYSTEM INSPECTION AND MAINTENANCE The following sections delineate thevarious maintenance activities to be performed on the landfill drainage facilities for the deck and slope areas. Figure 5 shows the location ofthe surface water drainage control facilities and Section 3.7 provides a description. After the control system has been in service for several years, a more definitive inspection and maintenance schedule can be developed identifying those facilities that must be inspected annually, those facilities that must be inspected prior to and after a storm and those facilities that require maintenance before the rainy season. 4.8.1 DECK DRAINAGE CONTROL SYSTEM FEATURES MAINTENANCE

PCFS FCPCMP Inspection for properdeck surface drainage (i.e. diversion berms, grading, etc.) will be performed in conjunction with the final cover procedures described in Section 4.4.2. It is importantthat maintenance vehicles utilize access roads 4-14 ]:\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010provided on the decks and benches whenever possible to reduce surface rutting which could interferewith the designed drainage patterns. 4.8.2 DOWNDRAINS, DRAINAGE CHANNELS, BASINS AND DITCHES A visual inspection ofeach downdrain, open channel and basin will be conducted to identify any ofthe following deficiencies:

• Cracking • Settlement • Spalling • Presence ofsilt and/or debris The following corrective measures can be taken for deficiencies identified during the inspection.

• Cracking

- Construction ofexpansion/controljoints

- Resurface

- Replacement • Settlement

- Grout injection

- Complete replacement with subgrade rework • Spalling

- Sandblast affected area and resurface

- Sawcut and remove affected area, dowel into existing undamaged section and resurface • Clogging by Silt/Debris

- Vacuum pumps

- Waterjet spray

- Bucket line

- Fire hose flushing The downdrains, open channels and basins shall be inspected annually for debris build-up prior to the rainy season and after high intensity storm events. 4.8.3 OVERALL DRAINAGE MAINTENANCE SCHEDULE The on-site drainage facilities must be free ofdebris and operational at all times.

PCFS FCPCMP 

### 4-15 ):\Imperial County\Picacho Ll\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010In orderto provide the desired protection againstflooding and erosion damage routine inspections ofthe drainage control system will be conducted as shown on Table 4. A written reportwill be prepared for all scheduled inspections and will be kept on file with the Site Engineer

. In addition, all inspection forms will be placed in the record library as required by40 CFR, 258.29. Form Eincluded in Appendix G is astandard inspection form, which can be used for this purpose. 

### 4.9 SITE SECURITY INSPECTION AND MAINTENANCE

4.10 4.1 0.1

4.10.2

PCFS FCPCMP Securityfencing, access gates and signs will be inspected quarterly to ensure that the integrity ofsite security has been maintained. The gates will be inspected to ensure that the locks are intact. Any necessary repairs or replacements will be made duringthe quarterly inspection. On an annual basis, the fence will be inspected for corrosion and rust, and maybe repainted as necessary to maintain the aesthetic quality ofthe site. 

### EQUIPMENT, LABOR AND MATERIAL REQUIREMENTS EQUIPMENT The equipment schedule presented in Table 5 delineates the specific type of equipment, instruments and tools expected to be used for post-closure maintenance. Any required equipment notavailable for on-site use, when necessary, will be rented on an "as needed" basis. LABOR The workforce necessary to monitor and maintain the PCFS during post-closure will be directed and coordinated bydesignated personnel. Staffwill be assigned to each ofthe following activities:

• Final cover, landscape, drainage and general maintenance • Environmental monitoring and reporting The maintenance and monitoring personnel will be underthe direction ofa Site Engineer or geologistwhere appropriate. 4-16 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec4.Doc; 10/21/2010PCFS FCPCMPThe projected maintenance schedule for each ofthe post-closure activities is shown on Table 4. The primary purpose ofthis schedule is to identifythe frequency of mandatory inspections forthe various systems. The frequency of sampling and analysis for the groundwater, perimeter gas probes and settlement monumentswill be in accordance with the monitoring schedule presented in Table 6. Any additional personnel needed forsurveying ordrillingwill be provided through outside contractors.

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## SECTION 5.0 POST-CLOSURE EMERGENCY RESPONSE PLAN

BRYAN A. STIRRAT & ASSOCIATES

## 5.0 POST-CLOSURE EMERGENCY RESPONSE PLAN

5.1 PURPOSE AND SCOPE This Emergency Response Plan (ERP) was prepared in accordance with 27 CCR, Section 21130 since 40 CFR, Part 258 does not require this plan, as part ofthe PCFS FCPCMP. The ERP identifies occurrences that may exceed the design of the site and endanger public health orthe environment. The ERP also sets forth actions thatwill minimize the effects ofthese catastrophic events. The provisions ofthis ERP will be carried out immediatelywhenever an event occurs such as a fire, explosion, flood, earthquake, vandalism, surface drainage problems or release ofany waste productwhich may threaten public health and/or the environment. The ERP will be kept in the operating record atthe CIDPW Main Office. 

### 5.2 

### SITE SAFETY OFFICER The Site Engineer will have the responsibility ofSite Safety Officer (SSO). The SSO will be trained to handle all emergency situations. The main responsibility ofthe SSO is to oversee the managementofall emergency response procedures implemented atthe landfill. The SSO is required to be thoroughlyfamiliar with all aspects ofthe ERP as well as all post-closure maintenance activities, the location and characteristics of buried refuse, the location offacility records and the overall site layout. In addition, the SSO shall be given the authority to commit any ofthe available resources necessary to carry outthe ERP. 

### 5.3 

### EMERGENCY RESPONSE NOTIFICATION PROCEDURE

PCFS FCPCMP When any memberofthe site's maintenance personnel discover orwitness an event, which constitutes an emergency situation, they shall determine the nature, source, and location ofthe emergency situation and immediately reportthe occurrence to the SSO. The SSO will notify all ofthe appropriate response agencies to provide assistance to site personnel. Ifan emergency event occurs when field personnel are noton-site, the general publicwill be able to use the telephone number posted on a sign to be located at the site entrance to notify the SSO. The emergency telephone numberwill be responded to 24 hours a day. 5-1 J:\lmperial County\Picacho U\2010.0044Fcpmp\Reports\PicsecS.Doc; 10/21/2010

### 5.4 

### EMERGENCY RESPONSE PROCEDURES General emergency response procedures for fire, explosions, earthquakes, floods, vandalism, release ofwaste products to air and soil, or surface drainage problems, are described below.

• Remove all non-essential employees from the vicinity ofthe incident. • Remove non-essential equipment, if itcan be done safely, from the vicinityof the incident. • Determine and identify the nearest source ofavailable equipmentand supplies for responding to the incident. • Determine the degree of risk to human health and safety for persons to be working in the vicinity ofthe emergency prior to sending in people to control the emergency. • Determine the immediate risk to the environment. Ifthe risk is imminent, it should be determined whether or notthe emergency can be safely isolated to minimize damage to the environment. • Determine the appropriate agencies to call given a particular type of emergency. • When practicable, the SSO may utilize on-site personnel to control the incident. • The Site Superintendent or his designee will be responsible for site personnel safety. Site personnel will communicate any damage and/or injury reports to the SSO and will coordinate all emergency actions directed bythe SSO. • Site personnel will be available for inspection ofthe landfill after an incident occurs. All crew members will be supplied with appropriate personal protective clothing, as required bythe SSO, when conducting inspections of the site for possible design failure. All findings will be reported to the SSO for action. • The SSO will immediately begin surveillance in those areas ofthe facility affected by the incident. In addition, monitoringwill be conducted to prevent an incidentfrom affecting other areas ofthe facility or adjacent properties. • Shut down any control system, which have been damaged during an incident. • The operatorwill maintain a small stockpile offinal cover material for those events, which may require immediate cover placementto minimize waste releases, to repair severe cracks, or to fill in large erosion gullies.

PCFS FCPCMP 5-2 J:\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\PicsecS.Doc; 10/21/2010The general types ofequipmentand materials that should be available for emergencies include a cellular phone, first aid kit, air supplies, fire extinguisher, final cover material, and sandbags. All action steps for the following emergency procedures should be done in as short a time period as possible to prevent adverse health and safety affects to the public. 

### 5.5 FIRE AND/OR EXPLOSIONS The following procedures will be followed during incidents offire and/or explosions:

• Contactthe County of Imperial Fire Department, even ifon-site capabilities are deemed adequate to extinguish fires or control future explosions. On-site landfill personnel will be instructed to follow the Fire Department's directions and give theirfull cooperation. • In the event ofan off-site fire near the landfill, such as a brush fire, the operatorwill lend its personnel and equipment, ifavailable, to the Fire Departmentto fight the fire. • The fire will be extinguished and the effects ofthe fire or explosion will be mitigated. The following are the general telephone numbers for emergency response agencies: 

# • Imperial County Fire Department 

### (760) 355-1191 

# • Imperial County Sheriff's Department 

### (760) 339-6302 

# • Office of Emergency Services 

### (800) 852-7550 

# • Imperial County Public Works Department 

### (760) 482-4462 

# • Imperial County Division of Environmental Health 

### (760) 336-8530 

## • Tribal Police, as needed 

### (760) 572-2933 

# • Tribal Environmental Department, as needed 

### (760) 572-2969 

# • Bureau of Indian Affairs (Regional Office), as needed 

### (602) 379-6600 

# • Tribal Emergency Response 

### (760) 572-0213 5.6 FLOOD

PCFS FCPCMP Ifthe site's existing stormwater diversion berms are inadequate in divertingflood waters away from the site, the following procedures will be followed:



### 5-3 ]:\Imperial County\Picacho U\2010.0044 Fcpmp\Reports\PicsecS.Doc; 10/21/2010• Additional berms may be constructed in areas prone to flooding. • Ifadditional berms are ineffective, the operator may cut a diversion channel to avoid inundation ofthe refuse cell. • Sandbags may be used in conjunction with berms or diversion channels. 

### 5.7 

### EARTHQUAKE The following procedures will be performed following an earthquake incident:

• Employees driving in the field during an earthquake should stop theirvehicle and get out, if it can be done in asafe manner. • Afterthe earthquake has subsided, site personnel shall report to the site entrance gate for a roll call. If medical care is required, the procedures in Section 5.10 shall be followed. An inspection ofthe site shall then be made and a report given to the SSO

. • Cracks observed in the final cover after an earthquake should be inspected with acombustible gas analyzer

.The location ofventing and the gas concentrations will be determined and reported to the SSO. Excavation and refill ofthe smaller surface cracks can be completed immediately. More extensive corrective actions will be authorized bythe Site Engineer in accordancewith the CQA Plan included in Appendix 1 ofAppendix D. 

### 5.8 

### SURFACE DRAINAGE PROBLEMS In the event ofa surface drainage problem, the following procedures shall be followed:

• The operatorwill investigate the problem and determine a necessary course ofaction. • Ifa surface inlet is blockedwith debris, all necessary laborforces and equipmentwill be implemented underthe direction ofthe operatorto remove the blockage

. • Ifa storm drain is damaged, a plan will be provided by the Site Engineer to repair the problem. • Afterthe drainage problem is corrected, an assessment ofpossible damage or erosion will be conducted and all necessary repairs will be made.

PCFS FCPCMP 

### 5-4 ]:\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\PicsecS.Doc; 10/21/2010

### 5.9 

### VANDALISM The following procedures will be followed during incidents ofvandalism:

• Repair (i.e., replace, repaint) any portion ofthe propertywhich has been vandalized

. • Immediately repair any vandalism, which affects site security and/or environmental control/monitoring systems. • A review ofthe adequacy ofsite security after each incident shall be performed and those measures will be revised, ifneeded. 

### 5.10 UNDERGROUND FIRES Underground landfill fires occur due to air intrusion into the refuse cell. Indicators ofunderground fires are as follows:

• Unusual depression-like settlementwith tension cracks • Smoke/steam • Unusual odor Should any ofthe above indicators be noted, the first course ofaction should be placement ofsoil to cover the depression and/or cracks. Ifthis measure does notcorrectthe problem, additional measures may be taken under the direction ofthe SSO. 

### 5.11 EMERGENCY RESPONSE PLAN ORIENTATION Contacts should be madewith appropriate emergency response agency representatives and the following information should be conveyed:

• Familiarize them with the layoutofthe facility, the properties ofthe waste materials deposited, and the evacuation routes
. • Establish understandings between the responding Police/Sheriffand Fire Departments and designate which agency has primary emergency authority during an incident. • Establish understandings between emergency response teams, emergency response contractors, and equipment suppliers for smooth coordination of emergency response actions.

PCFS FCPCMP 

### 5-5 ]:\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\PicsecS.Doc; 10/21 /2010

### 5.12 EVACUATION PROCEDURES During and/or after an incident, the SSO in consultation with other emergency personnel, such as the Fire Department, will assess the potential for injury to any persons located on adjacent properties. Ifthe assessment concludes that an imminentthreatto public health is possible, an evacuation ofthe nearbyarea will be initiated. Situations, which warrant partial or complete evacuation ofsite personnel and/or local residents, are as follows:

• Explosions resulting in airborne debris including particles and large fragments. • Fires that cannot be readily contained or are spreading to other parts ofthe facility; orwhen fire could generate highly toxic fumes, or create a danger of igniting potentially explosive substances which may be stored on-site. The SSO will immediately notifythe responding Police/Sheriff Departmentand all other appropriate emergency response agencies. The SSO will check thatthe entrance gate is unlocked and locked as required. 

### 5.13 MEDICAL CARE PROCEDURES Should an emergency situation result in personal injury, immediate steps will be taken to determine the cause and extentofthe injury and to render first aid. The SSO will be notified in all cases and the paramedics will be called when required. Iffurther medical attention is necessary, the injured person will be transported to the nearest medical facility. 

### 5.14 AMENDMENTS TO THE EMERGENCY RESPONSE PLAN

PCFS FCPCMP The ERP will be reviewed and can be amended, in accordance with the criteria listed in 27 CCR, Section 21130(c). The amendment criteria are as follows:

• A failure or release occurs forwhich the plan did not provide an appropriate response. • The post-closure use and/or structures on the site change and these changes are notaddressed in the existing plan. • The LEA, the RWQCB orthe CIWMB notifies the operator in writing thatthe current emergency response plan is inadequate underthe provisions ofthis section. The notifying agency shall includewithin the written noticethose items that must be considered for the plan to be in compliance with this 

### 5-6 ):\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\PicsecS.Doc; 10/21/2010

### section. The operator shall submitan amended ERP to the Quechan Indian Tribe, LEA, the RWQCB and the CIWMBwithin 30 days ofreceipt of notification thatthe plan is inadequate. Wheneverthe ERP is amended, awritten copywill be submitted to the Quechan Tribal Council.

PCFS FCPCMP 

### 5-7 J:\lmperial County\Pitacho Lf\2010.0044 Fcpmp\Reports\PicsecS.Doc; 10/21/2010

## SECTION 6.0 CLOSURE/POST-CLOSURE MAINTENANCE COSTESTIMATE

BRYANA. STIRRAT&ASSOCIATES

## 6.0 CLOSURE/POST-CLOSURE MAINTENANCE COST ESTIMATE

6.1 INTRODUCTION In orderto establish the basis for the proper level offunding to close and provide post-closure maintenance for the PCFS in an environmentally sound manner, a cost estimatewas prepared reflecting closure plan features and post-closure maintenance procedures presented in Section 4.0 ofthe this FCPCMP. This estimate was then combined with an estimate for construction management/quality assurance services to determine the total closure cost. This closure and post-closure cost estimate then serves as the basis tofund the closure accountoverthe life ofthe landfill. 

### 6.2 CLOSURE COST ESTIMATE The plan features are grouped into categories for convenience in presenting the estimate. A briefdescription ofthe components included in each category is given below. The closure cost estimate, as shown in 201 0 dollars, is shown on Table 

### 7. 6.2.1 FINAL COVER

PCFS FCPCMP The PCFS disposal area at closure will be 12.5 acres. The planned final coverfor the deck and slope areas consists ofatwo-footthick foundation layer composed ofselect soil materials, a minimum onefoot ofwhich has been determined to be in-place by the recent existing cover evaluation, and a two and a halffoot thick layer ofselect soil material thatwill comprise the monolithicvegetative cover layer with a soil/pit run rock admixture layer in the upper six to eight inches. The cost ofconstructing the final cover includes the use ofon-site or near-site select soils, importofpit run rock material for the soil/pit run rock admixture, site preparation, and closure plan integration with the existing groundwater monitoring system. The final grading costalso includes access road/staging area construction.

6-1 J:\lmperial County\Picacho Ll\2010.0044 Fcpmp\Reports\Picsec6.Doc; 10/21/20106.2.2 FINAL COVER CONSTRUCTION QUALITYASSURANCE Costs for construction quality assurance include the final cover placementtests, inspections and reporting. 6.2.3 DRAINAGE CONTROL SYSTEM Costs for drainage system improvements include the deck and V-channel drainage improvements for the landfill. 6.2.4 EROSION CONTROL This category covers the cost ofsoil preparation and mixture of pit run rock materials into the top six inches ofthe monolithicvegetative layer as discussed in Section 3.3. 6.2.5 GAS MIGRATION MONITORING SYSTEM This category includes costs for installation offour multiple-depth gas migration monitoring probes around the perimeter ofthe PCFS as discussed in Section 3.8. 6.2.6 GROUNDWATER MONITORING SYSTEM No costs are associated with this category since no additional groundwater monitoringwells are planned to be installed at closure. 6.2.7 SITE SECURITY This category includes costs for installation ofadditional perimeterfencing to secure the entire filled area ofthe site at closure. This category also includes signage as discussed in Section 3.11. 6.2.8 DEMOLITION

PCFS FCPCMPThis category includes costs for dismantling and removal ofthe landfill scales and scalehouse.

6-2 ]:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec6.Doc; 10/21/20106.2.9 CLOSURE CERTIFICATION REPORT

6.2.10

6.2.11 This category includes costs for preparation ofa report certifying the final cover placement. ENGINEERING DESIGN PLANS AND SPECIFICATIONS This category includes costs for preparation ofconstruction level engineering design plans and specifications for bid purposes. This cost estimate is assumed to be five percentofthe total construction cost estimate. CONSTRUCTION MANAGEMENT The construction managementcostfor closure ofthe landfill is based on an estimated 3-month construction schedule. 

### 6.3 

### POST-CLOSURE MAINTENANCE COST ESTIMATE The post-closure maintenance cost estimate has been prepared utilizing information contained in Tables 3 through 5 and estimates of manpower, material and equipmentto maintain the PCFS in compliance with current applicable regulations. The total annual maintenance and monitoring cost estimate for post-closure is shown on Table 8. These costs are projected in 2010 dollars, assuming no change in the regulatory environmentwith respect to the PCFS. In the eventthat changes occur in the regulatory conditions pertaining to the PCFS, if necessary, revised post-closure cost estimates will be submitted to the USEPA, the Quechan Tribal Council, CIDPW, and LEA. 

### 6.4 

### DEMONSTRATION OF FINANCIAL RESPONSIBILITY

PCFS FCPCMP In accordance with Subtitle D, Subpart G, the CIDPW must demonstrate financial responsibility for closure and post-closure costs. The CIDPW has established an enterprise fund for closure costs and a Pledge of Revenue has been established for post-closure maintenance costs to complywith financial assurance requirements of40 CFR 258.71-72. Subsequentto their review ofthe FCPCMP for PCFS (dated May 1999; revised: June 2009), the United States Environmental Protection Agency - Region 9 approved the revised cost estimate 

### 6-3 ):\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec6.Doc; 10/21/2010PCFS FCPCMP included in the aforementioned FCPCMP and found thatthe CIDPW meets the Local GovernmentTestfor allowable mechanisms as outlined in 40 CFR 258.74(f). A copy ofthe most up-to-date closure and post-closure cost estimate can be found in the operating record. The closure and post-closure cost estimates are adjusted for inflation annually as required by 40 CFR 258.71-72.

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### SECTION 7.0 RECORDKEEPING

BRYAN A. STIRRAT & ASSOCIATES

### 7.0 RECORDKEEPING

7.1 OPERATING RECORD A complete operating record will be maintained in accordance with Federal regulations 40 CFR 258 (Section 258.29 Recordkeeping Requirements and Section 258.60 Closure Criteria). Closure and post-closure activities will be documented in the operating record and will include, butwill not be limited to, the following information:

• Any location restriction demonstration required by 40 CFR 258, Subpart B; • Inspection records, training records, and notification procedures required by 40 CFR 258, Section 258.20; • Gas monitoring results from monitoring and any remediation plans required by 40 CFR 258, Section 258.23; • Any MSWLF unitdesign documentation for placement ofleachate and gas condensate in a MSWLD unitas required under40 CFR 258, Section 258.28(a)(2); • Any demonstration, certification, finding, monitoring, testing or analytical data required by 40 CFR 258, Subpart E; • Closure and post-closure care plans and any monitoring, testing, or analytical data required by 40 CFR 258, Sections 258.60- 258.61; • Any cost estimates and financial assurance documentation required by 40 CFR 258, Subpart G; • Any information demonstrating compliance with small community exemption as required by 40 CFR 258, Section 258.1 (f)(2); and • Notice of intentto close the unit, notice ofcertification ofclosure, and deed notation as required by 40 CFR 258, Section 258.60. Itshould be noted thatthe operating record will also contain that information compiled during active operations as required by applicable Federal regulations. 

### 7.2 LOCATION AND INSPECTION OF OPERATING RECORDS

PCFS FCPCMPThe operating records will be maintained atthe CIDPW's Main Office. In accordance with 40 CFR 258, Section 258.29, the CIWMB has been notified of the alternative location (i.e., the Main Office) ofthe operating record for the 7-1 ]:\Imperial County\Picacho Lt\2010.0044 Fcpmp\Reports\Picsec7.Doc; 10/21/2010PCFS FCPCMP PCFS. These records are openfor inspection during normal business hours by authorized representativesofthose regulatory agencies havingjurisdiction over the PCFS.



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### SECTION 8.0 REFERENCES

BRYAN A. STIRRAT & ASSOCIATES

### 8.0 REFERENCES 1. Code of Federal Regulations Title 40, Parts 257 and 258. 2. California Code of Regulations, Title 27, Chapters 3 and 4. 3. Blake, T.F., 2000a, EQFAULT, A Computer Program for the Estimation of Peak Horizontal Acceleration from 3-D Fault Sources, Version 3.00b, Updated 2004. 4. Blake, T.F., 2000b, EQSEARCH, A Computer Program for the Estimation of Peak Horizontal Acceleration from California Historical Earthquake Catalogs, Version 3.00, Updated 2009. 5. Bray, J.D., and Rathje, E.M., 1998, "Earthquake-Induced Displacements ofSolidWaste Landfills," Journal ofGeotechnical and Geoenvironmental Engineering, ASCE, March, Vol. 124, No.3. 6. Bray, J.D., E.M. Rathje, A.J. Augello, and S.M. Merry, 1998, Simplified Seismic Design Procedure for Geosynthetic-Lined, Solid Waste Landfills, Geosynthetics International, Vol. 5, Nos. 1-2, 1998. 7. Bryan A. Stirrat & Associates, Inc., June 1995, Revised August 1995, 11Preliminary Closure and Post-Closure Maintenance Plan. 11 8. Imperial County Public Works Department, March 1995, 11Periodic Site Review, Picacho Solid Waste Site, Winterhaven, California. 11 9. HerzogAssociates, October 1988, 11Solid Waste Water QualityAssessmentTest (SWAT) Proposal, Picacho Solid Waste Disposal Site, County of Imperial, California. 11 10. ENVIRON Corporation, August 1994, "Work Plan Ground Water Monitoring Program Ocotillo, Salton City, Hot Spa, Niland, Palo Verde and Picacho Landfills. 11 11. Campbell, K.W., 1993, 11Empirical Prediction of Near-Source Ground Motion from Large Earthquakes," Proceedings, International Workshop on Earthquake Hazard and Large Dams in the Himalaya, Sponsored bythe Indian National Trust for Art and Cultural Heritage (INTACH), New Delhi, India, January 15-16. 12. Loeltz, O.J., Irelan, B., Rubison, J.H., and Olmsted, F.J., 1975, 11Geohydrologic Reconnaissance ofthe Imperial Valley, California, U.S. Geological Survey Professional Paper 486-K. 11 13. Moore & Taber, 1988, 11Seismic and Hydrogeologic Review, IT Corporation Class I Waste Disposal Site, Imperial County, California. 11 14. Newmark, N.M., 1965, "Effects of Earthquakes on Dams and Embankments," Geotechnique, Vol. 15(2), pp. 139-160.

PCFS FCPCMP 8-1 (J:\Imperial County\Picacho Lf\2010.0044 Fcpmp\Reports\Picsec8.Doc; 10/21/2010)15. Singh, S., and Murphy, Bruce, "Evaluation ofthe Stability ofSanitary Landfills", In: 

### CeotechnicsofWaste Fills

- Theor yandPractice, ASTM STP 1070, Arvid Landvia, G. David Knowles, editors, American Society forTesting Materials, Philadelphia, 1990. 16. County of Imperial, Departmentof Public Works, Imperial Solid Waste Sites, Waste Volume and Remaining Capacity, and Quarterly Solid Waste Reports. 17
. California Integrated Waste Management Board, September 8, 1998, letter re: Adequacy ofthe Closure/Postclosure Maintenance Fund forthe Worthington, Calexico, Ocotillo, Holtville, Palo Verde, Brawley, Niland, HotSpa, Salton City, Picacho. 18
. California Regional Water Quality Control Board - Colorado River Region, 1988, "Waste Discharge Requirements Order No. 88-5." 19
. California Regional Water Quality Control Board- Colorado River Region, 1993, "Amended Waste Discharge Requirements Order No. 93-071." 20
. California Integrated Waste Management Board, 1980, "Solid Waste Facilities Permit No. 13-AA-0012."

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